Such a radial piston pump has a pump housing and at least one pump unit comprising a pump piston and a cylinder insert, in which the pump piston is mounted such that it can be moved to and fro, it being possible for the pump unit to be driven by way of a camshaft mounted in the pump housing and for a roller plunger to be arranged between the camshaft and the pump unit.
A generic radial piston pump is already known from EP 1 319 831 A2. The radial piston pump has a camshaft, which moves a piston arranged in the pump housing and/or cylinder head by way of a roller plunger. The roller plunger is arranged between the camshaft and the pump piston and features a plunger as well as a roller which are essentially directly arranged in the plunger in a rotatable manner. The outer peripheral area of the roller rolls on the outer peripheral area of the camshaft. This produces especially low friction at the point of contact between the roller and the camshaft, thereby minimizing the wear of the components.
Such a solution is however disadvantageous in that the roller plunger is only guided in an axial direction. It is however not possible to prevent the roller plunger from rotating about its longitudinal axis. This means that the roller of the roller plunger can no longer roll accurately on the cam of the camshaft, which can result, in an extreme case, in a total failure of the radial piston pump.